District police often plead for help from the public, asking them to call when something seems suspicious or to cooperate upon witnessing a crime. But when people saw a man snatch a purse off a woman’s shoulder Friday night in Mount Pleasant, they did more than simply call 911.

They chased the man, caught him and held him until police came and put him in handcuffs.

“You can’t just stand around,” said Rember Compres, a 19-year-old waiter who said he saw “a big man running with a purse” and quickly took off after him. He didn’t realize he had joined a posse until he looked back.

“There were 10 other people chasing the guy,” Compres said.

Authorities said the robbery occurred at about 8:45 p.m. near Park Road and Hiatt Place Northwest, close to restaurants and other businesses. Authorities said the woman’s brown purse was ripped from her right hand. The woman told police that she started running after the culprit, screaming, “He stole my purse.”

D.C. Police Sgt. James Boteler, who is with the vice unit that made the eventual arrest, said bystanders and patrons of a restaurant leapt into action. “It was almost a neighborhood effort,” he said. “Somebody yelled, ‘Get him!’ and about 10 people took off after this guy.”

Compres, who waits tables at Los Hermanos, a Dominican restaurant on Park Road, said he was walking toward his workplace when the man with the purse ran by him. He said he was able to briefly stop and confront him. “I said, ‘Give back the purse,’ ” Compres said. “I pushed him and we tussled.” He said the man then shouted, “I’ll stab you,” and threw the purse at him and ran away.

But Compres said the man still had the woman’s wallet, so he and others continued the chase, which ended about two blocks away in the 1600 block of Lamont Street NW, near the Mount Pleasant Library, where the suspect was tackled as he tried to hide under a car. The people who chased him surrounded the man until police arrived. No knife was found.

A police spokesman identified the suspect as Terrance Mobley, 28, of Rockville, Md. He has been charged with one count of robbery. At a Saturday hearing, D.C. Superior Court Judge Gerald I. Fisher ordered Mobley detained until a preliminary hearing scheduled for Tuesday.

D.C. Police Cmdr. Diane Groomes, chief of the patrol division, posted a congratulatory note on the department’s intranet bulletin board. “The citizens in this case should be commended for their utmost bravery, assistance to [the Metropolitan Police Department] and their compassion for the victim,” the note says.

Boteler, the police sergeant, said the suspect saw an opportunity to take a purse and “fortunately people didn’t want it to happen in their neighborhood. We don’t want people to become vigilantes, but it is nice that they took action.”